JP2018052793A - Ferrite composition and electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ferrite composition which is used in a small-sized DC-DC converter, has such frequency characteristics as to operate as an inductor in a high frequency region and DC superimposition characteristics that hardly vary even when applied to large current, and has good initial permeability, specific resistance, frequency characteristics and temperature characteristics, and to provide an electronic component using the ferrite composition.SOLUTION: A ferrite composition contains, as main components, 18-30 mol% of iron oxide in terms of FeO, 4-14 mol% of iron oxide in terms of CuO, 0-6 mol% of zinc oxide in terms of ZnO, and the balance being nickel oxide, contains, with respect to 100 pts.wt. of the main components, as accessory components, 0.30-1.83 pts.wt. of a silicon compound in terms of SiO, 2.00-10.00 pts.wt. of a cobalt compound in terms of CoO, and 1.00-3.00 pts.wt. of a bismuth compound in terms of BiO, where a value obtained by dividing the content of the cobalt compound in terms of CoOby the content of the silicon compound in terms of SiOis 5.5-30.0.SELECTED DRAWING: None

Description

  The present invention relates to a ferrite composition suitable for manufacturing a multilayer inductor and the like, and an electronic component having a ferrite sintered body composed of the composition.

  In recent years, DC-DC converters have become smaller and have higher frequencies, and some of them are driven at a frequency of about several tens of MHz to several hundreds of MHz. As an inductor applied to a DC-DC converter that is downsized and increased in frequency, a frequency characteristic that operates as an inductor even in a high frequency region and a DC superposition characteristic that hardly changes in operation even when a large current is applied are required.

  As a ferrite composition used for an inductor applied to a DC-DC converter, NiCuZn ferrite added with cobalt has been proposed. A technique for improving magnetic anisotropy and improving frequency characteristics of magnetic permeability by adding cobalt to NiCuZn ferrite has been studied.

  However, it has been known for a long time that NiCuZn ferrite added with cobalt tends to have lower sinterability and lower temperature characteristics than NiCuZn ferrite not added with cobalt. The following method has been proposed as a method for overcoming the drawbacks of the above cobalt addition.

  In Patent Document 1, a decrease in sinterability is overcome by adding a bismuth compound such as bismuth oxide together with a cobalt compound to NiCuZn ferrite. Furthermore, it is trying to improve temperature characteristics by adding a zirconium compound.

In Patent Document 2, it is attempted to obtain high Q value, good temperature characteristics, and high anti-stress characteristics by adding Co ₃ O ₄ , SiO ₂ , Bi ₂ O ₃ to NiCuZn ferrite.

In Patent Document 3, an attempt is made to obtain a ferrite composition having excellent frequency characteristics by relatively reducing the amount of Fe ₂ O ₃ and ZnO in NiCuZn ferrite and further adding CoO.

However, in the example of Patent Document 1, although the value of the initial permeability μ _i is shown, there is no description as to how high the magnetic permeability value is held. According to the Snake limit, the permeability value is generally held up to a higher frequency as the value of the initial permeability μ _i is lower. However, when an additive is added, the magnetic permeability is maintained up to a frequency higher than the limit of the snake, or conversely, the magnetic permeability decreases at a low frequency lower than the limit of the snake. For this reason, the initial permeability μ _i is a measure of the frequency characteristics, but the basis for the evaluation of the frequency characteristics is poor. Therefore, in the example of Patent Document 1, the frequency characteristic is unknown.

In addition, the limit of a snake is represented by the following formula | equation (1). Note that f _r rotational magnetization resonance frequency, mu _i is the initial permeability, gamma is the gyromagnetic constant, M _s is the saturation magnetization.
f _r (μ _i −1) = | γ | × (M _s / 3π) (1)

  Patent Document 1 shows the ratio between the initial permeability at 20 ° C. and the initial permeability at 85 ° C. with respect to the temperature change of the permeability when zirconium oxide is added. However, the smallest ratio of the initial permeability at 20 ° C. and the initial permeability at 85 ° C. shown in the example of Patent Document 1 is 1.45 times. This result is too large to suppress the change in the initial permeability with respect to the temperature change.

  Moreover, in patent document 2, the value of initial magnetic permeability is not shown and the frequency characteristic is unknown. In Patent Document 3, the temperature characteristics are unknown. Further, in each of Patent Documents 1 to 3, the DC superposition characteristics are unknown.

  From the above, it is unclear whether the NiCuZn ferrites of Patent Documents 1 to 3 are excellent in frequency characteristics, DC superposition characteristics, and temperature characteristics.

JP 2000-252112 A JP 2006-206347 A JP 2008-300548 A

  The present invention has been made in view of such a situation, and an object thereof is to provide a ferrite composition having good initial magnetic permeability, specific resistance, frequency characteristics, and temperature characteristics, and an electronic component using the ferrite composition. It is.

In order to achieve the above object, a ferrite composition according to the present invention is a ferrite composition having a main component and a subcomponent,
The main component is composed of iron oxide in an amount of 18 to 30 mol% in terms of Fe ₂ O ₃ , copper oxide in an amount of 4 to 14 mol% in terms of CuO, zinc oxide in an amount of 0 to 6 mol% in terms of ZnO, and the remainder composed of nickel oxide. And
With respect to 100 parts by weight of the main component, as subcomponents, the silicon compound is 0.30 to 1.83 parts by weight in terms of SiO ₂ and the cobalt compound is 2.00 to 10.00 parts by weight in terms of Co ₃ O _4. , 1.00 to 3.00 parts by weight of Bi ₂ O _{3 in} terms of Bi ₂ O ₃ ,
A value obtained by dividing the content of the cobalt compound in terms of Co ₃ O ₄ by the content of the silicon compound in terms of SiO ₂ is 5.5 to 30.0.

The ferrite composition according to the present invention has a content of the oxide constituting the main component within the above range, and further contains silicon compounds, cobalt compounds, and bismuth compounds as subcomponents within the above range. The initial permeability μ _i , the specific resistance ρ, the frequency characteristic, and the temperature characteristics of the initial permeability μ _i are good.

  The reason why such an effect can be obtained is considered to be a composite effect obtained by setting the main component within a predetermined range and further setting the content of each component within a specific range.

  The electronic component according to the present invention has a ferrite sintered body composed of the above ferrite composition.

  The ferrite sintered body constituted by the ferrite composition according to the present invention is suitably used for a multilayer inductor, a multilayer LC filter, a multilayer common mode filter, a composite electronic component using another multilayer construction method, and the like. . For example, the ferrite composition according to the present invention is suitably used for LC composite electronic components, NFC coils, multilayer impedance elements, and multilayer transformers.

FIG. 1 is a cross-sectional view of a multilayer inductor according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of an LC composite electronic component according to an embodiment of the present invention. FIG. 3 is a schematic diagram of the frequency characteristics of magnetic permeability in NiCuZn ferrite.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
As shown in FIG. 1, a multilayer inductor 1 according to an embodiment of the present invention includes an element 2 and a terminal electrode 3. The element 2 is obtained by firing a green laminate in which the coil conductor 5 is formed three-dimensionally and spirally through the ferrite layer 4. The ferrite layer 4 is composed of a ferrite composition according to an embodiment of the present invention. The multilayer inductor 1 is obtained by forming the terminal electrode 3 at both ends of the element 2 and connecting it to the terminal electrode 3 through the extraction electrodes 5a and 5b. Although there is no restriction | limiting in particular in the shape of the element 2, Usually, it is set as a rectangular parallelepiped shape. Moreover, there is no restriction | limiting in particular also in the dimension, What is necessary is just to set it as a suitable dimension according to a use.

  The material of the coil conductor 5 and the extraction electrodes 5a and 5b is not particularly limited, and Ag, Cu, Au, Al, Pd, Pd / Ag alloy or the like is used. A Ti compound, Zr compound, Si compound, or the like may be added.

  The ferrite composition according to the present embodiment is Ni-Cu ferrite or Ni-Cu-Zn ferrite, and contains iron oxide, copper oxide and nickel oxide as main components, and further contains zinc oxide. Good.

In the main component 100 mol%, the content of iron oxide, calculated as _Fe 2 _{O 3} is from 18.0 to 30.0 mol%. If the content of iron oxide is too much or too little, the sinterability tends to deteriorate, and the sintering density particularly during low-temperature sintering tends to decrease. In addition, when the amount of iron oxide is too small, the initial permeability μ _i tends to decrease. When there is too much iron oxide, the frequency characteristics deteriorate, and the μ ″ rising frequency described later tends to decrease. Further, the temperature characteristics of the initial permeability μ _i tend to deteriorate.

In 100 mol% of the main component, the content of copper oxide is 4 to 14 mol% in terms of CuO. When there is too little content of copper oxide, sinterability will deteriorate and it exists in the tendency for the sintered density at the time of low temperature sintering to fall especially. As a result, the temperature characteristics of the specific resistance ρ and the initial permeability μ _i tend to deteriorate. If the amount is too large, the initial permeability μ _i tends to decrease.

  In 100 mol% of the main component, the content of zinc oxide is 0 to 6.0 mol% in terms of ZnO. That is, zinc oxide may or may not be contained as a main component. The initial permeability tends to increase as the zinc oxide content increases, and the higher the initial permeability, the more suitable for the inductor. However, when the content of zinc oxide is too large, the Curie temperature and the μ ″ rising frequency tend to decrease.

  The remainder of the main component is composed of nickel oxide.

  The ferrite composition according to this embodiment contains a silicon compound, a cobalt compound, and a bismuth compound as subcomponents in addition to the above main component. The type of each compound is not particularly limited as long as it becomes an oxide after firing in addition to the oxide.

The content of the silicon compound is 0.30 to 1.83 parts by weight in terms of SiO _{2 with} respect to 100 parts by weight of the main component. When the silicon compound is contained within a specific range, the temperature characteristics of the ferrite composition are improved. When the content of the silicon compound is too small, the temperature characteristics of the initial permeability μ _i tend to be lowered. When the amount is too large, the sinterability is deteriorated, and the sintering density at the time of low-temperature sintering tends to decrease. Further, the initial permeability μ _i and the specific resistance ρ tend to decrease.

  The reason why the temperature characteristics are improved by the addition of the silicon compound will be described. Silicon compounds such as silicon oxide have a smaller coefficient of linear expansion than NiCuZn ferrite particles. That is, when a silicon compound is added to NiCuZn ferrite to form a ferrite composition, the added silicon compound applies stress to the NiCuZn ferrite in advance. The present inventors consider that since the stress caused by the presence of the silicon compound exists, the influence of the stress caused by the temperature change is alleviated and the temperature characteristics are improved.

The content of the bismuth compound is 1.00 to 3.00 parts by weight in terms of Bi ₂ O _{3 with} respect to 100 parts by weight of the main component. The silicon compound described above and the cobalt compound described later have the effect of reducing the sinterability. On the other hand, the bismuth compound increases the sinterability and enables firing at a temperature of 900 ° C. or lower. When the content of the bismuth compound is too small, the sinterability is deteriorated, and in particular, the sintered density during low-temperature sintering tends to be lowered. Furthermore, the specific resistance ρ tends to decrease as the sinterability deteriorates. When there is too much content of a bismuth compound, it exists in the tendency for specific resistance (rho) to fall.

The content of the cobalt compound, relative to 100 parts by weight of the main component, with _Co 3 _{O 4} conversion is from 2.00 to 10.00 parts by weight. When the cobalt compound is contained within a specific range, the frequency characteristics are improved and the μ ″ rising frequency is improved. Furthermore, direct current superimposition characteristics are also improved. That is, a decrease in inductance when DC current is superimposed is reduced. When the content of the cobalt compound is too small, the frequency characteristics are deteriorated and the μ ″ rising frequency tends to be lowered. Furthermore, the specific resistance ρ tends to decrease. When the amount is too large, the sinterability is deteriorated, and the sintering density at the time of low-temperature sintering tends to decrease. As a result, the initial permeability μ _i also tends to decrease. Furthermore, the temperature characteristics of the initial permeability μ _i tend to deteriorate.

Furthermore, in the ferrite composition according to the present embodiment, a value obtained by dividing the content of the cobalt compound converted to Co ₃ O ₄ on the weight basis by the content of the silicon compound converted to SiO ₂ on the weight basis (hereinafter referred to as Co / (Denoted as Si) is 5.5 to 30.0.

The above Co / Si limitation indicates that the allowable range of the cobalt compound content increases or decreases depending on the silicon compound content. Even if the content of the cobalt compound is 10.0 parts by weight or less, the temperature characteristic of the initial permeability μ _i deteriorates when Co / Si exceeds 30.0 due to the small amount of silicon compound added. Tend to. Further, even when the content of the cobalt compound is 2.0 parts by weight or more, when Co / Si is less than 5.5, the specific resistance ρ and the initial permeability μ _i tend to decrease. In addition, the frequency characteristics are reduced as compared with a sample having the same magnetic permeability, and the μ ″ rising frequency is reduced.

In the ferrite composition according to this embodiment, in addition to the composition range of the main component being controlled within the above range, the silicon compound, bismuth compound and cobalt compound are all within the scope of the present invention as subcomponents. It is contained in. As a result, the sintering temperature can be lowered, and a metal having a relatively low melting point such as Ag can be used as the internal conductor to be integrally fired. Furthermore, the ferrite sintered body obtained by low-temperature firing has high initial permeability, good frequency characteristics, high specific resistance ρ, good direct current superposition characteristics, and good temperature characteristics. In particular, the temperature characteristics of the μ ″ rising frequency and the initial permeability μ _i are improved by the interaction between the cobalt compound and the silicon compound.

  In addition, when one or more of silicon compounds, bismuth compounds, and cobalt compounds are not contained, or when the content is outside the scope of the present invention, the above effects cannot be obtained sufficiently. . That is, the above effect is considered to be a composite effect obtained only when a specific amount of silicon compound, bismuth compound and cobalt compound is contained at the same time.

Further, the ferrite composition according to the present embodiment, in addition to the subcomponents described above, further contains additional components such as manganese oxides such as Mn ₃ O ₄ , zirconium oxide, tin oxide, magnesium oxide, and glass compounds. You may contain in the range which does not inhibit an effect. Although content of these additional components is not specifically limited, For example, it is about 0.05 to 10 weight%.

  Furthermore, the ferrite composition according to the present embodiment may include oxides of inevitable impurity elements.

  Specifically, unavoidable impurity elements include C, S, Cl, As, Se, Br, Te, I, Li, Na, Mg, Al, Ca, Ga, Ge, Sr, Cd, In, Sb. And typical metal elements such as Ba, Pb, and transition metal elements such as Sc, Ti, V, Cr, Y, Nb, Mo, Pd, Ag, Hf, and Ta. Moreover, the oxide of an unavoidable impurity element may be contained in the ferrite composition as long as it is about 0.05% by weight or less.

  The ferrite composition according to the present embodiment has ferrite particles and crystal grain boundaries that exist between adjacent crystal particles. The average crystal particle diameter of the crystal particles is preferably 0.2 to 1.5 μm.

  Next, frequency characteristics of the ferrite composition of the present invention will be described.

  The frequency characteristic of the ferrite composition of the present invention indicates whether or not the magnetic permeability can be maintained up to a high frequency.

  In order to explain the frequency characteristics of the ferrite composition of the present invention, for a general NiCuZn ferrite, the frequency is taken on the horizontal axis, and the real part μ ′ and the imaginary part μ ″ of the complex permeability are taken on the vertical axis. A schematic diagram of is shown in FIG.

  In the low frequency region, μ ′ is substantially constant even when the frequency is changed, and μ ″ is substantially constant near 0. When the frequency is increased to a specific frequency or higher, μ ″ rises from 0. In the present application, the frequency at which μ ″> 0.1 is set as the μ ″ rising frequency.

  In a frequency range higher than the μ ″ rising frequency, the Q value decreases, making it difficult to use as an inductor. Therefore, the higher the μ ″ rise frequency of the ferrite composition of the present invention, the higher the upper limit of the frequency that can be used as an inductor. The ferrite composition of the present invention has better frequency characteristics as the μ ″ rise frequency is higher. Hereinafter, the μ ″ rising frequency may be expressed as f.

  Next, an example of a method for producing a ferrite composition according to this embodiment will be described. First, starting materials (raw materials of main components and raw materials of subcomponents) are weighed and mixed so as to have a predetermined composition ratio to obtain a raw material mixture. Examples of the mixing method include wet mixing using a ball mill and dry mixing using a dry mixer. It is preferable to use a starting material having an average particle size of 0.05 to 1.0 μm.

As a raw material for the main component, iron oxide (α-Fe ₂ O ₃ ), copper oxide (CuO), nickel oxide (NiO), zinc oxide (ZnO), or a composite oxide as required can be used. . In addition, various compounds that become oxides or composite oxides by firing can be used. Examples of the oxide that becomes the above-mentioned oxide upon firing include simple metals, carbonates, oxalates, nitrates, hydroxides, halides, organometallic compounds, and the like.

  Silicon oxide, bismuth oxide, and cobalt oxide can be used as a raw material for the accessory component. There is no particular limitation on the oxide that is a raw material of the subcomponent, and a composite oxide or the like can be used. In addition, various compounds that become oxides or composite oxides by firing can be used. Examples of the oxide that becomes the above-mentioned oxide upon firing include simple metals, carbonates, oxalates, nitrates, hydroxides, halides, organometallic compounds, and the like.

Note that Co ₃ O ₄ which is one form of cobalt oxide is preferable as a raw material for cobalt oxide because it is easy to store and handle and has a stable valence even in air.

  Next, the raw material mixture is calcined to obtain a calcined material. Calcining causes thermal decomposition of raw materials, homogenization of ingredients, formation of ferrite, disappearance of ultrafine powder due to sintering and grain growth to an appropriate particle size, and converts the raw material mixture into a form suitable for the subsequent process. Done for. Such calcination is preferably performed at a temperature of 500 to 900 ° C., usually for about 2 to 15 hours. The calcination is usually performed in the atmosphere (air), but may be performed in an atmosphere having a lower oxygen partial pressure than in the atmosphere. The mixing of the main component raw material and the subcomponent raw material may be performed before calcining or after calcining.

  Next, the calcined material is pulverized to obtain a pulverized material. The pulverization is performed in order to break down the coagulation of the calcined material to obtain a powder having appropriate sinterability. When the calcined material forms a large lump, wet pulverization is performed using a ball mill or an attritor after coarse pulverization. The wet pulverization is performed until the average particle diameter of the pulverized material is preferably about 0.1 to 1.0 μm.

  Using the obtained pulverized material, the multilayer inductor according to this embodiment is manufactured. A method for manufacturing the multilayer inductor is not limited, but in the following, a sheet method is used.

  First, the obtained pulverized material is slurried together with additives such as a solvent and a binder to prepare a paste. Then, a green sheet is formed using this paste. Next, the formed green sheet is processed into a predetermined shape, and a multilayer inductor according to this embodiment is obtained through a binder removal step and a firing step. Firing is performed at a temperature below the melting point of the coil conductor 5 and the extraction electrodes 5a and 5b. For example, when the coil conductor 5 and the extraction electrodes 5a and 5b are Ag (melting point 962 ° C.), the temperature is preferably 850 to 920 ° C. The firing time is usually about 1 to 5 hours. The firing may be performed in the atmosphere (air) or in an atmosphere having a lower oxygen partial pressure than in the atmosphere. The multilayer inductor thus obtained is composed of the ferrite composition according to this embodiment.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to such embodiment at all, Of course, in the range which does not deviate from the summary of this invention, it can implement in various aspects. . For example, the ferrite composition of the present invention may be used as the ferrite layer 4 in the LC composite electronic component 10 shown in FIG. In FIG. 2, the part indicated by reference numeral 12 is an inductor part, and the part indicated by reference numeral 14 is a capacitor part.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.

First, Fe ₂ O ₃ , NiO, CuO, and ZnO were prepared as main component materials. SiO ₂ , Bi ₂ O ₃ , and Co ₃ O ₄ were prepared as subcomponent materials.

  Next, the prepared main components were weighed so as to have the compositions shown in Tables 1 to 4 as sintered bodies, and then wet-mixed with a ball mill for 16 hours to obtain a raw material mixture.

  Next, after the obtained raw material mixture was dried, it was calcined at 500 ° C. to 900 ° C. in the air to obtain a calcined powder. The calcined powder and the raw material powder of the accessory component were wet pulverized for 72 hours with a steel ball mill to obtain a pulverized powder.

Next, after drying this pulverized powder, 10.0 parts by weight of a 6 wt% polyvinyl alcohol aqueous solution as a binder was added to 100 parts by weight of the pulverized powder, and granulated to give granules. This granule is subjected to pressure molding to form a toroidal shape (dimension = outer diameter 13 mm × inner diameter 6 mm × height 3 mm) and a disk shape (dimension = outer diameter) so that the molding density is 3.20 Mg / m ^3. A molded body of 12 mm × height 2 mm) was obtained.

Next, each of these molded bodies was fired in air at 900 ° C., which is lower than the melting point of Ag (962 ° C.) for 2 hours, to obtain a toroidal core sample as a sintered body. Furthermore, the following characteristics evaluation was performed with respect to the sample. The test results are shown in Tables 1 to 4. The content of each component described in Table 1 to Table 4 is a value in terms of each _{Fe 2 O 3, NiO, CuO} , ZnO, SiO 2, Co 3 O 4, Bi 2 O 3.

Initial permeability μ _i
A copper wire was wound around the toroidal core sample for 10 turns, and an initial permeability μ _i was measured using an impedance analyzer (4991A manufactured by Agilent Technologies). The measurement conditions were a measurement frequency of 1 MHz and a measurement temperature of 25 ° C. In this example, the case where the initial permeability μ _i was 1.5 or more was considered good.

Frequency characteristics (μ '' rise frequency)
With respect to the toroidal core sample whose initial permeability μ _i was measured, μ ″ was measured while increasing the measurement frequency from 1 MHz. The frequency when μ ″ exceeded 0.1 was defined as the μ ″ rising frequency. When the μ ″ rising frequency f is 600 MHz or more, the frequency characteristics are good.

Specific resistance ρ
In-Ga electrodes were coated on both sides of the disk sample, the DC resistance value was measured, and the specific resistance ρ was determined (unit: Ω · m). The measurement was performed using an IR meter (4329A manufactured by HEWLETT PACKARD). In this example, the case where the specific resistance ρ was 10 ⁶ Ω · m or more was considered good.

With respect to the temperature characteristic room 25 ° C. of initial permeability mu _i, determine the rate of change of the initial permeability mu _i at 25 ° C. to 125 ° C.. In this example, the case where the rate of change of μ _i was within ± 30% was considered good.

  In the sample of Table 1, all compositions other than Co and Si were made the same within the scope of the present invention, and the content of Si was fixed at 0.33, 0.36, or 0.40 parts by weight. It is a sample in which only the content is changed.

From Table 1, when the composition of all the main components and subcomponents is within the range of the present invention, the initial magnetic permeability μ _i , the specific resistance ρ, the frequency characteristics, and the temperature characteristics of the initial magnetic permeability μ _i are good. It was.

  On the other hand, the samples 1, 11 and 21 in which the content of Co as a minor component is too small are not preferable in terms of frequency characteristics or specific resistance ρ. The Co content is within the scope of the present invention, but the specific resistance ρ is also not preferable for the sample 22 in which Co / Si is too small.

Further, Samples 7, 17 and 27 having too much Co content are not preferable in terms of temperature characteristics of initial permeability μ _i . Sample 27 is also unfavorable in terms of initial permeability μ _i . Furthermore, although the Co content is within the range of the present invention, the temperature characteristic of the initial permeability μ _i is not preferable for the sample 6 in which Co / Si is too large.

  In the sample of Table 2, all compositions other than Co and Si were the same within the scope of the present invention, and the Co content was fixed at 2.00, 4.80, 9.00, or 10.00 parts by weight. In this sample, only the Si content was changed.

From Table 2, when the composition of all the main components and subcomponents is within the range of the present invention, the initial magnetic permeability μ _i , the specific resistance ρ, the frequency characteristics, and the temperature characteristics of the initial magnetic permeability μ _i are good. It was.

On the other hand, the samples 31, 36, 41, and 46 having a small Si content as a subsidiary component are not preferable for the temperature characteristics of the initial permeability μ _i . Further, the Si content is within the range of the present invention, but the temperature characteristic of the initial permeability μ _i is not preferable for the sample 47 having too large Co / Si.

In addition, the sample 50 having too much Si content is not preferable in terms of the initial permeability μ _i and the specific resistance ρ. Furthermore, although the Si content is within the range of the present invention, the samples 22, 40 and 45 having too small Co / Si are not preferable in specific resistance ρ. Samples 40 and 45 are also unfavorable in terms of initial permeability μ _i .

  The sample of Table 3 is a sample in which the content of the main component is changed from the sample 12.

From Table 3, when the composition of all the main components and subcomponents is within the range of the present invention, the initial magnetic permeability μ _i , the specific resistance ρ, the frequency characteristics, and the temperature characteristics of the initial magnetic permeability μ _i are good. It was.

In contrast, Comparative Examples content of the main component is outside the scope of the present invention, the specific resistance [rho, frequency characteristic, temperature characteristic and / or initial permeability mu _i of initial permeability mu _i becomes an unfavorable value It was.

  Samples 91 to 95 in Table 4 are samples in which the composition other than Bi is the same as that of sample 12 and only the Bi content is changed. Moreover, about the samples 12 and 91-95 of Table 4, the relative density was also measured in order to confirm sinterability.

  The relative density is measured by calculating the sintered body density from the size and weight of the sintered body after firing, and calculating the sintered body density relative to the theoretical density. Calculated as In this example, the relative density was determined to be 95% or more.

From Table 4, when the composition of all the main components and subcomponents is within the scope of the present invention, the initial permeability μ _i , the specific resistance ρ, the relative density (sinterability), the frequency characteristics, and the initial permeability μ The temperature characteristic of _i was good.

On the other hand, the relative density of the sample 91 in which the Bi content was too small was low. That is, the sinterability of the sample 91 was extremely reduced. As a result, the initial permeability μ _i and the specific resistance ρ became unfavorable values. In addition, the specific resistance ρ of the sample 95 having too much Bi content deteriorated.

DESCRIPTION OF SYMBOLS 1 ... Multilayer inductor 2 ... Element 3 ... Terminal electrode 4 ... Laminated body 5 ... Coil conductor 5a, 5b ... Extraction electrode 10 ... LC composite electronic component 12 ... Inductor part 14 ... Capacitor part

Claims (2)

A ferrite composition having a main component and a subcomponent,
The main component is composed of iron oxide in an amount of 18 to 30 mol% in terms of Fe ₂ O ₃ , copper oxide in an amount of 4 to 14 mol% in terms of CuO, zinc oxide in an amount of 0 to 6 mol% in terms of ZnO, and the remainder composed of nickel oxide. And
With respect to 100 parts by weight of the main component, as subcomponents, the silicon compound is 0.30 to 1.83 parts by weight in terms of SiO ₂ and the cobalt compound is 2.00 to 10.00 parts by weight in terms of Co ₃ O _4. , 1.00 to 3.00 parts by weight of Bi ₂ O _{3 in} terms of Bi ₂ O ₃ ,
A ferrite composition, wherein a value obtained by dividing the content of the cobalt compound converted to Co ₃ O ₄ by the content of the silicon compound converted to SiO ₂ is 5.5 to 30.0.   An electronic component having a ferrite sintered body composed of the ferrite composition according to claim 1.

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